The present invention is directed to a vapor recovery system and, more particularly, to a vapor recovery system having a valve positioned in the nozzle to assist in determining leaks along the vapor recovery system including the hanging hardware.
Vapor recovery equipped fuel dispensers, particularly gasoline dispensers, have been known for quite some time, and have been mandatory in California for a number of years. The primary purpose of using a vapor recovery fuel dispenser is to retrieve or recover vapors that would otherwise be emitted to the atmosphere during a fueling operation, particularly for motor vehicles. The vapors of concern are generally those which are contained in the vehicle gas tank. As liquid gasoline is pumped into the tank, the vapor is displaced and forced out through the filler pipe. Other volatile hydrocarbon liquids raise similar issues. In addition to the need to recover vapors, some states, California in particular, are requiring extensive reports about the efficiency with which vapor is recovered and proof that the vapor recovery systems are working as intended.
A traditional vapor recovery apparatus is known as a xe2x80x9cbalancexe2x80x9d system, in which a sheath or boot encircles the liquid fueling spout and connects by tubing back to a fuel reservoir. As the liquid enters the tank, the vapor is forced into the sheath and back toward the fuel reservoir or underground storage tank (UST) where the vapors can be stored or recondensed. Balance systems have numerous drawbacks, including cumbersomeness, difficulty of use, ineffectiveness when the seals are poorly made, and slow fueling rates.
As a dramatic step to improve on the balance systems, Gilbarco, Inc., assignee of the present invention, patented an improved vapor recovery system for fuel dispensers, as seen in U.S. Pat. No. 5,040,577, now Reissue Patent No. 35,238 to Pope, which is herein incorporated by reference in its entirety. The Pope patent discloses a vapor recovery apparatus having a vapor pump in the vapor return line driven by a variable speed motor. The liquid flow line includes a pulser, conventionally used for generating pulses indicative of the liquid fuel being pumped. This permits computation of the total sale and the display of the volume of liquid dispensed and the cost in a conventional display. A microprocessor translates the pulses indicative of the liquid flow rate into a desired vapor pump operating rate. The effect is to permit the vapor to be pumped at a rate correlated with the liquid flow rate so that, as liquid is pumped faster, vapor is also pumped faster.
Previous systems have been developed to test for leaks in the vapor recovery line. U.S. Pat. Nos. 5,450,883 and 5,857,500 both assigned to Gilbarco, Inc. and incorporated herein by reference in their entirety, disclose vacuum-assisted vapor recovery systems having vapor valves positioned within the vapor recovery line between the nozzle and vacuum pump and between the vapor pump and underground storage tank. Both systems include pressure sensors to detect leaks in the vapor recovery system, and may include a valve in the dispenser nozzle. However, the valves are manually operated requiring trained personnel or technicians to physically open and close the valves in the nozzle and check for leaks in the vapor recovery system.
The present invention allows for detecting a leak within a vapor recovery system, including the hanging hardware. A valve positioned in the vapor recovery line within the hanging hardware is selectively positionable between open and closed positions. In one embodiment, when the hanging hardware is in an upright, or vertical position such as when not in use, an attitude valve positioned in the nozzle is in a closed position. A vapor pump is positioned on the vapor recovery line downstream of the valve to create a vacuum within the line to draw vapors during the fueling process. A pressure sensor is also located on the vapor recovery line for detecting the amount of pressure within the line. A control system monitors the vapor pump and pressure sensor and compares the sensor readings with values stored in memory. A leak is detected when the detected pressure in the vapor recovery differs from the stored value.
The invention may further include additional valves positioned along the vapor recovery line. Each of the valves is operatively connected to the control system which positions each between open and closed orientations. Leaks in the vapor recovery system can be determined and isolated by testing individual sections of the vapor recovery line and comparing the values. In either embodiment, if the control system identifies a leak, the fueling system may be shut down, or a signal sent to a technician or user indicating the leak and that service is required.
A method of performing the testing along the portions of the vapor recovery line are also included within the invention. One method of testing includes using a single valve within the hanging hardware. When the valve is closed, the vapor pump is initiated and a pressure reading is obtained within the vapor recovery line. The pressure is compared to an expected value previously stored in the control system and if the values differ, a leak is determined to exist.
A second method uses the valve within the hanging hardware, and at least one additional valve placed along the vapor recovery line. A first pressure reading is performed by closing the additional valve and determining the vapor pressure within the line between the additional valve and the vapor pump. The additional valve is then opened, and the hanging hardware valve is closed to determine a second vapor pressure between the hanging hardware valve and the vapor pump. The first and second vapor pressures are compared to determine whether there are any leaks within the vapor recovery line. Additionally, the approximate location of the leak may be determined by comparing the vapor pressures from each section. If both sections indicate a leak, the leak is located at a point shared by both sections. Likewise, if only one section indicates a leak, the leak is located at a point not commonly shared by both sections. Notably, the systems and methods described above can be modified such that a vapor pump creates a positive pressure or a negative pressure in the vapor recovery line.
Another method closes one of the valves and creates a pressure within the vapor recovery line. The pressure, either positive or negative, is determined by the pressure sensor and then maintained for a period of time. Afterwards, the pressure is again tested and a leak within the vapor recovery line will result in a change in the pressure.